In a modern disk storage device operating at a high storage density and close tolerances it is a particular problem to control the environment within that portion of the disk storage device which contains the recording disks and the read/write heads. To ensure proper operation and high reliability of the disk storage device, the humidity within the enclosure containing the disks and read/write heads must be tightly regulated, and solid and gaseous contaminants must be excluded. An enclosure for a disk storage drive enclosure is typically formed as a clam shell configuration including a bottom cast metal mounting base and a top cover.
In a disk storage device, a cable is generally used to electrically couple the internal components, such as the read/write heads, with external components, such as a controller. A typical cable that is suitable for such purposes is formed as a flat ribbon-like flexible multi-conductor cable having a lateral extent substantially greater than its thickness. Such a cable is sometimes known as a flexible circuit or "flexcircuit." In a disk storage device of the type constructed in a clam shell configuration, the area that is most prone to leakage of water vapor, solid contaminants, and corrosive gases is in the vicinity where the cable or flexcircuit is fed between the base and cover of the enclosure.
Various feedthrough techniques are known for routing a cable having a substantially circular profile through an opening in a wall of a sealed enclosure. However, these techniques are generally not readily adaptable to a flat cable such as a flexcircuit. Known techniques which are specifically tailored for flat cables generally involve multiple parts and may require tedious manual assembly to achieve a good seal about the flexcircuit.
One technique for achieving a sealed feedthrough for a flat cable utilizes a molded header consisting of several parts. Typically, the wires are individually separated out of the flexcircuit and positioned at predetermined positions within the header. Then the various parts of the header are clamped together around the wires to maintain an environmental seal. The header is then placed inside the opening of the enclosure with appropriate grommets or gaskets to provide the seal between the header and the enclosure. Alternatively the header is formed with embedded conductive lugs, and the wires of the cable are individually soldered to lugs on opposing sides of the header. Another technique uses injection molding to form a cylindrically shaped plug around the flat cable. The plug and embedded cable are then inserted into a round opening in the the enclosure. O-rings may also be placed in grooves formed around the periphery of the plug to improve the seal between the plug and the walls of the opening in the enclosure.
Other methods of sealing an enclosure of a disk storage device may make use of gaskets. Typically, the gasket is placed between the base and cover portions of the enclosure, the flexcircuit is placed across the seal, and held in place by compressing the base and cover against the gasket. Such a gasket is typically constructed as a specially molded silicone O-ring, a die cut foam seal, a molded rubber seal, adhesive tape, or combinations thereof. Seals of this type require cleaning before they can be applied, and also require a substantial amount of manual dexterity to assemble. However, if assembled incorrectly, seals of the gasket types are prone to leak. Even when assembled correctly, such seals may still leak since the seal relies on compressing the seal material over the flexcircuit. Invariably, after assembly, at either side of the flexcircuit there is a small gap that is not filled completely by the sealing material no matter how hard it is compressed. These gaps are potential leak areas for water vapor, corrosive gases and solid contaminants. Some techniques attempt to correct this deficiency by placing additional pieces of sealing material under or around the flexcircuit, however a good fit at the edges of the flexcircuit is difficult to achieve.
Accordingly, the known techniques for sealing a disk storage device increase labor, rework, and cost, and moreover, do not always guarantee an impervious seal.
Therefore, it is desirable to provide an apparatus for sealing about a flexcircuit of a disk storage device which is simple to manufacture and easy to install.